The present invention relates to a device in a motor saw comprising a housing and a guide bar provided with a saw chain, said guide bar being releasably attatched at one end to the housing and axially slidable by means of an adjusting means in order to adjust the tension of the saw chain.
In order to adjust the axial position of the guide bar and thereby adjust the stretching of the chain it is common practice to use an adjusting screw extending parallel to the guide bar and actuating a stretching pin engaging a bore in the guide bar. The advantage of a screw device is that it is self-braking which facilitates the adjustment in that the adjusted position is maintained during tightening of the guide bar locking bolts, and also in that it contributes to maintaining the guide bar in its adjusted position during operation. The disadvantage is that the adjusting screw is not easily accessible whereby the adjusting is more circumstantial to carry out than would be preferable.
Another proposed arrangement comprises a gear wheel engaging a rack and having a shaft which extends through a bore in the guide bar and is thereby easily accessible for adjustment. A device of this type is described in DE 4104576. The disadvantage of this device, however, is that it is not self-braking which makes it difficult to maintain the guide bar in its adjusted position.